Move GC Forms app off of the alpha domain

### Description
As part of our roadmap and for our ATO, we need to move GC Forms app from its current alpha domain to a Canada.ca domain.

We will follow the same process as GC Sign In, [as outlined here](https://docs.google.com/document/d/1LXf5mnLR5TuX1Q3RNcDDb-nROxgfrW5VlL6Pzpg6dRQ/edit?tab=t.0).

### Acceptance Criteria:
- [x] Complete research/investigation - see [#2686](https://app.zenhub.com/workspaces/gcforms-60cb8929764d71000e481cab/issues/gh/cds-snc/platform-forms-client/2686)
- [x] Complete the [Subdomain Registration Form](https://014gc.sharepoint.com/:w:/r/sites/CDS-Migration-Take3/Shared%20Documents/CDS%20Policy%20-%20SNC%20Politiques/GC%20Forms/English-Subdomain-Request-Form%20-%20GC%20Forms%202026.docx?d=w7f6602711b4a42af805fec4714a66e9c&csf=1&web=1&e=7h8jOJ)
- [x] Send the Subdomain Registration Form to ESDC’s AEM institutional representatives who will approve it and set up a ticket with Principal Publisher
- [ ] Receive DNS record data from Principal Publisher
- [ ] Configure DNS record and issue SSL certificate
- [ ] [Update policy process guide with timeline](https://docs.google.com/document/d/1LXf5mnLR5TuX1Q3RNcDDb-nROxgfrW5VlL6Pzpg6dRQ/edit?tab=t.0#heading=h.nfz9enld2xjq)

### Definition of Done
- GC Forms domain is https://forms-formulaires.canada.ca/